License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.
By default all files without license information are under the default
license of the kernel, which is GPL version 2.
Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.
How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,
Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.
The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.
The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.
Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that became
the concluded license(s).
- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 14:07:57 +00:00
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/* SPDX-License-Identifier: GPL-2.0 */
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2011-05-26 23:25:24 +00:00
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#ifndef VM_EVENT_ITEM_H_INCLUDED
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#define VM_EVENT_ITEM_H_INCLUDED
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#ifdef CONFIG_ZONE_DMA
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#define DMA_ZONE(xx) xx##_DMA,
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#else
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#define DMA_ZONE(xx)
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#endif
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#ifdef CONFIG_ZONE_DMA32
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#define DMA32_ZONE(xx) xx##_DMA32,
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#else
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#define DMA32_ZONE(xx)
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#endif
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#ifdef CONFIG_HIGHMEM
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2015-11-06 02:48:50 +00:00
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#define HIGHMEM_ZONE(xx) xx##_HIGH,
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2011-05-26 23:25:24 +00:00
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#else
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#define HIGHMEM_ZONE(xx)
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#endif
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2022-08-07 15:44:42 +00:00
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#ifdef CONFIG_ZONE_DEVICE
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#define DEVICE_ZONE(xx) xx##_DEVICE,
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#else
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#define DEVICE_ZONE(xx)
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#endif
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#define FOR_ALL_ZONES(xx) DMA_ZONE(xx) DMA32_ZONE(xx) xx##_NORMAL, \
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HIGHMEM_ZONE(xx) xx##_MOVABLE, DEVICE_ZONE(xx)
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2011-05-26 23:25:24 +00:00
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enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
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2022-08-07 15:44:42 +00:00
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FOR_ALL_ZONES(PGALLOC)
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FOR_ALL_ZONES(ALLOCSTALL)
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FOR_ALL_ZONES(PGSCAN_SKIP)
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2017-05-03 21:52:29 +00:00
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PGFREE, PGACTIVATE, PGDEACTIVATE, PGLAZYFREE,
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2011-05-26 23:25:24 +00:00
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PGFAULT, PGMAJFAULT,
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mm: support madvise(MADV_FREE)
Linux doesn't have an ability to free pages lazy while other OS already
have been supported that named by madvise(MADV_FREE).
The gain is clear that kernel can discard freed pages rather than
swapping out or OOM if memory pressure happens.
Without memory pressure, freed pages would be reused by userspace
without another additional overhead(ex, page fault + allocation +
zeroing).
Jason Evans said:
: Facebook has been using MAP_UNINITIALIZED
: (https://lkml.org/lkml/2012/1/18/308) in some of its applications for
: several years, but there are operational costs to maintaining this
: out-of-tree in our kernel and in jemalloc, and we are anxious to retire it
: in favor of MADV_FREE. When we first enabled MAP_UNINITIALIZED it
: increased throughput for much of our workload by ~5%, and although the
: benefit has decreased using newer hardware and kernels, there is still
: enough benefit that we cannot reasonably retire it without a replacement.
:
: Aside from Facebook operations, there are numerous broadly used
: applications that would benefit from MADV_FREE. The ones that immediately
: come to mind are redis, varnish, and MariaDB. I don't have much insight
: into Android internals and development process, but I would hope to see
: MADV_FREE support eventually end up there as well to benefit applications
: linked with the integrated jemalloc.
:
: jemalloc will use MADV_FREE once it becomes available in the Linux kernel.
: In fact, jemalloc already uses MADV_FREE or equivalent everywhere it's
: available: *BSD, OS X, Windows, and Solaris -- every platform except Linux
: (and AIX, but I'm not sure it even compiles on AIX). The lack of
: MADV_FREE on Linux forced me down a long series of increasingly
: sophisticated heuristics for madvise() volume reduction, and even so this
: remains a common performance issue for people using jemalloc on Linux.
: Please integrate MADV_FREE; many people will benefit substantially.
How it works:
When madvise syscall is called, VM clears dirty bit of ptes of the
range. If memory pressure happens, VM checks dirty bit of page table
and if it found still "clean", it means it's a "lazyfree pages" so VM
could discard the page instead of swapping out. Once there was store
operation for the page before VM peek a page to reclaim, dirty bit is
set so VM can swap out the page instead of discarding.
One thing we should notice is that basically, MADV_FREE relies on dirty
bit in page table entry to decide whether VM allows to discard the page
or not. IOW, if page table entry includes marked dirty bit, VM
shouldn't discard the page.
However, as a example, if swap-in by read fault happens, page table
entry doesn't have dirty bit so MADV_FREE could discard the page
wrongly.
For avoiding the problem, MADV_FREE did more checks with PageDirty and
PageSwapCache. It worked out because swapped-in page lives on swap
cache and since it is evicted from the swap cache, the page has PG_dirty
flag. So both page flags check effectively prevent wrong discarding by
MADV_FREE.
However, a problem in above logic is that swapped-in page has PG_dirty
still after they are removed from swap cache so VM cannot consider the
page as freeable any more even if madvise_free is called in future.
Look at below example for detail.
ptr = malloc();
memset(ptr);
..
..
.. heavy memory pressure so all of pages are swapped out
..
..
var = *ptr; -> a page swapped-in and could be removed from
swapcache. Then, page table doesn't mark
dirty bit and page descriptor includes PG_dirty
..
..
madvise_free(ptr); -> It doesn't clear PG_dirty of the page.
..
..
..
.. heavy memory pressure again.
.. In this time, VM cannot discard the page because the page
.. has *PG_dirty*
To solve the problem, this patch clears PG_dirty if only the page is
owned exclusively by current process when madvise is called because
PG_dirty represents ptes's dirtiness in several processes so we could
clear it only if we own it exclusively.
Firstly, heavy users would be general allocators(ex, jemalloc, tcmalloc
and hope glibc supports it) and jemalloc/tcmalloc already have supported
the feature for other OS(ex, FreeBSD)
barrios@blaptop:~/benchmark/ebizzy$ lscpu
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
CPU(s): 12
On-line CPU(s) list: 0-11
Thread(s) per core: 1
Core(s) per socket: 1
Socket(s): 12
NUMA node(s): 1
Vendor ID: GenuineIntel
CPU family: 6
Model: 2
Stepping: 3
CPU MHz: 3200.185
BogoMIPS: 6400.53
Virtualization: VT-x
Hypervisor vendor: KVM
Virtualization type: full
L1d cache: 32K
L1i cache: 32K
L2 cache: 4096K
NUMA node0 CPU(s): 0-11
ebizzy benchmark(./ebizzy -S 10 -n 512)
Higher avg is better.
vanilla-jemalloc MADV_free-jemalloc
1 thread
records: 10 records: 10
avg: 2961.90 avg: 12069.70
std: 71.96(2.43%) std: 186.68(1.55%)
max: 3070.00 max: 12385.00
min: 2796.00 min: 11746.00
2 thread
records: 10 records: 10
avg: 5020.00 avg: 17827.00
std: 264.87(5.28%) std: 358.52(2.01%)
max: 5244.00 max: 18760.00
min: 4251.00 min: 17382.00
4 thread
records: 10 records: 10
avg: 8988.80 avg: 27930.80
std: 1175.33(13.08%) std: 3317.33(11.88%)
max: 9508.00 max: 30879.00
min: 5477.00 min: 21024.00
8 thread
records: 10 records: 10
avg: 13036.50 avg: 33739.40
std: 170.67(1.31%) std: 5146.22(15.25%)
max: 13371.00 max: 40572.00
min: 12785.00 min: 24088.00
16 thread
records: 10 records: 10
avg: 11092.40 avg: 31424.20
std: 710.60(6.41%) std: 3763.89(11.98%)
max: 12446.00 max: 36635.00
min: 9949.00 min: 25669.00
32 thread
records: 10 records: 10
avg: 11067.00 avg: 34495.80
std: 971.06(8.77%) std: 2721.36(7.89%)
max: 12010.00 max: 38598.00
min: 9002.00 min: 30636.00
In summary, MADV_FREE is about much faster than MADV_DONTNEED.
This patch (of 12):
Add core MADV_FREE implementation.
[akpm@linux-foundation.org: small cleanups]
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Mika Penttil <mika.penttila@nextfour.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Jason Evans <je@fb.com>
Cc: Daniel Micay <danielmicay@gmail.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Shaohua Li <shli@kernel.org>
Cc: <yalin.wang2010@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: "Shaohua Li" <shli@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chen Gang <gang.chen.5i5j@gmail.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Helge Deller <deller@gmx.de>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Roland Dreier <roland@kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Shaohua Li <shli@kernel.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-16 00:54:53 +00:00
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PGLAZYFREED,
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2016-07-28 22:45:31 +00:00
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PGREFILL,
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2020-08-21 23:49:58 +00:00
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PGREUSE,
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2016-07-28 22:45:31 +00:00
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PGSTEAL_KSWAPD,
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PGSTEAL_DIRECT,
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2022-10-26 18:01:33 +00:00
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PGSTEAL_KHUGEPAGED,
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2025-03-18 07:58:32 +00:00
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PGSTEAL_PROACTIVE,
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2016-07-28 22:45:31 +00:00
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PGSCAN_KSWAPD,
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PGSCAN_DIRECT,
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2022-10-26 18:01:33 +00:00
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PGSCAN_KHUGEPAGED,
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2025-03-18 07:58:32 +00:00
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PGSCAN_PROACTIVE,
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2012-07-31 23:44:39 +00:00
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PGSCAN_DIRECT_THROTTLE,
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2020-06-03 23:02:34 +00:00
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PGSCAN_ANON,
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PGSCAN_FILE,
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PGSTEAL_ANON,
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PGSTEAL_FILE,
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2011-05-26 23:25:24 +00:00
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#ifdef CONFIG_NUMA
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2024-07-22 17:13:16 +00:00
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PGSCAN_ZONE_RECLAIM_SUCCESS,
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2011-05-26 23:25:24 +00:00
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PGSCAN_ZONE_RECLAIM_FAILED,
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#endif
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2012-04-25 23:01:48 +00:00
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PGINODESTEAL, SLABS_SCANNED, KSWAPD_INODESTEAL,
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2011-05-26 23:25:24 +00:00
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KSWAPD_LOW_WMARK_HIT_QUICKLY, KSWAPD_HIGH_WMARK_HIT_QUICKLY,
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2016-07-28 22:46:59 +00:00
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PAGEOUTRUN, PGROTATED,
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2014-04-03 21:48:19 +00:00
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DROP_PAGECACHE, DROP_SLAB,
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2017-07-06 22:40:28 +00:00
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OOM_KILL,
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2012-11-02 14:52:48 +00:00
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#ifdef CONFIG_NUMA_BALANCING
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NUMA_PTE_UPDATES,
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2013-11-12 23:08:32 +00:00
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NUMA_HUGE_PTE_UPDATES,
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2012-11-02 14:52:48 +00:00
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NUMA_HINT_FAULTS,
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NUMA_HINT_FAULTS_LOCAL,
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NUMA_PAGE_MIGRATE,
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sched/numa: add statistics of numa balance task
On systems with NUMA balancing enabled, it has been found that tracking
task activities resulting from NUMA balancing is beneficial. NUMA
balancing employs two mechanisms for task migration: one is to migrate
a task to an idle CPU within its preferred node, and the other is to
swap tasks located on different nodes when they are on each other's
preferred nodes.
The kernel already provides NUMA page migration statistics in
/sys/fs/cgroup/mytest/memory.stat and /proc/{PID}/sched. However, it
lacks statistics regarding task migration and swapping. Therefore,
relevant counts for task migration and swapping should be added.
The following two new fields:
numa_task_migrated
numa_task_swapped
will be shown in /sys/fs/cgroup/{GROUP}/memory.stat, /proc/{PID}/sched
and /proc/vmstat.
Introducing both per-task and per-memory cgroup (memcg) NUMA balancing
statistics facilitates a rapid evaluation of the performance and
resource utilization of the target workload. For instance, users can
first identify the container with high NUMA balancing activity and then
further pinpoint a specific task within that group, and subsequently
adjust the memory policy for that task. In short, although it is
possible to iterate through /proc/$pid/sched to locate the problematic
task, the introduction of aggregated NUMA balancing activity for tasks
within each memcg can assist users in identifying the task more
efficiently through a divide-and-conquer approach.
As Libo Chen pointed out, the memcg event relies on the text names in
vmstat_text, and /proc/vmstat generates corresponding items based on
vmstat_text. Thus, the relevant task migration and swapping events
introduced in vmstat_text also need to be populated by
count_vm_numa_event(), otherwise these values are zero in /proc/vmstat.
In theory, task migration and swap events are part of the scheduler's
activities. The reason for exposing them through the
memory.stat/vmstat interface is that we already have NUMA balancing
statistics in memory.stat/vmstat, and these events are closely related
to each other. Following Shakeel's suggestion, we describe the
end-to-end flow/story of all these events occurring on a timeline for
future reference:
The goal of NUMA balancing is to co-locate a task and its memory pages
on the same NUMA node. There are two strategies: migrate the pages to
the task's node, or migrate the task to the node where its pages
reside.
Suppose a task p1 is running on Node 0, but its pages are located on
Node 1. NUMA page fault statistics for p1 reveal its "page footprint"
across nodes. If NUMA balancing detects that most of p1's pages are on
Node 1:
1.Page Migration Attempt:
The Numa balance first tries to migrate p1's pages to Node 0.
The numa_page_migrate counter increments.
2.Task Migration Strategies:
After the page migration finishes, Numa balance checks every
1 second to see if p1 can be migrated to Node 1.
Case 2.1: Idle CPU Available
If Node 1 has an idle CPU, p1 is directly scheduled there. This
event is logged as numa_task_migrated.
Case 2.2: No Idle CPU (Task Swap)
If all CPUs on Node1 are busy, direct migration could cause CPU
contention or load imbalance. Instead: The Numa balance selects a
candidate task p2 on Node 1 that prefers Node 0 (e.g., due to its own
page footprint). p1 and p2 are swapped. This cross-node swap is
recorded as numa_task_swapped.
Link: https://lkml.kernel.org/r/d00edb12ba0f0de3c5222f61487e65f2ac58f5b1.1748493462.git.yu.c.chen@intel.com
Link: https://lkml.kernel.org/r/7ef90a88602ed536be46eba7152ed0d33bad5790.1748002400.git.yu.c.chen@intel.com
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Cc: Aubrey Li <aubrey.li@intel.com>
Cc: Ayush Jain <Ayush.jain3@amd.com>
Cc: "Chen, Tim C" <tim.c.chen@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Libo Chen <libo.chen@oracle.com>
Cc: Mel Gorman <mgorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-05-23 12:51:15 +00:00
|
|
|
NUMA_TASK_MIGRATE,
|
|
|
|
|
NUMA_TASK_SWAP,
|
2012-11-02 14:52:48 +00:00
|
|
|
#endif
|
2012-10-19 09:46:20 +00:00
|
|
|
#ifdef CONFIG_MIGRATION
|
|
|
|
|
PGMIGRATE_SUCCESS, PGMIGRATE_FAIL,
|
2020-08-12 01:31:51 +00:00
|
|
|
THP_MIGRATION_SUCCESS,
|
|
|
|
|
THP_MIGRATION_FAIL,
|
|
|
|
|
THP_MIGRATION_SPLIT,
|
2012-10-19 09:46:20 +00:00
|
|
|
#endif
|
2011-05-26 23:25:24 +00:00
|
|
|
#ifdef CONFIG_COMPACTION
|
2012-10-19 11:00:10 +00:00
|
|
|
COMPACTMIGRATE_SCANNED, COMPACTFREE_SCANNED,
|
|
|
|
|
COMPACTISOLATED,
|
2011-05-26 23:25:24 +00:00
|
|
|
COMPACTSTALL, COMPACTFAIL, COMPACTSUCCESS,
|
mm, compaction: introduce kcompactd
Memory compaction can be currently performed in several contexts:
- kswapd balancing a zone after a high-order allocation failure
- direct compaction to satisfy a high-order allocation, including THP
page fault attemps
- khugepaged trying to collapse a hugepage
- manually from /proc
The purpose of compaction is two-fold. The obvious purpose is to
satisfy a (pending or future) high-order allocation, and is easy to
evaluate. The other purpose is to keep overal memory fragmentation low
and help the anti-fragmentation mechanism. The success wrt the latter
purpose is more
The current situation wrt the purposes has a few drawbacks:
- compaction is invoked only when a high-order page or hugepage is not
available (or manually). This might be too late for the purposes of
keeping memory fragmentation low.
- direct compaction increases latency of allocations. Again, it would
be better if compaction was performed asynchronously to keep
fragmentation low, before the allocation itself comes.
- (a special case of the previous) the cost of compaction during THP
page faults can easily offset the benefits of THP.
- kswapd compaction appears to be complex, fragile and not working in
some scenarios. It could also end up compacting for a high-order
allocation request when it should be reclaiming memory for a later
order-0 request.
To improve the situation, we should be able to benefit from an
equivalent of kswapd, but for compaction - i.e. a background thread
which responds to fragmentation and the need for high-order allocations
(including hugepages) somewhat proactively.
One possibility is to extend the responsibilities of kswapd, which could
however complicate its design too much. It should be better to let
kswapd handle reclaim, as order-0 allocations are often more critical
than high-order ones.
Another possibility is to extend khugepaged, but this kthread is a
single instance and tied to THP configs.
This patch goes with the option of a new set of per-node kthreads called
kcompactd, and lays the foundations, without introducing any new
tunables. The lifecycle mimics kswapd kthreads, including the memory
hotplug hooks.
For compaction, kcompactd uses the standard compaction_suitable() and
ompact_finished() criteria and the deferred compaction functionality.
Unlike direct compaction, it uses only sync compaction, as there's no
allocation latency to minimize.
This patch doesn't yet add a call to wakeup_kcompactd. The kswapd
compact/reclaim loop for high-order pages will be replaced by waking up
kcompactd in the next patch with the description of what's wrong with
the old approach.
Waking up of the kcompactd threads is also tied to kswapd activity and
follows these rules:
- we don't want to affect any fastpaths, so wake up kcompactd only from
the slowpath, as it's done for kswapd
- if kswapd is doing reclaim, it's more important than compaction, so
don't invoke kcompactd until kswapd goes to sleep
- the target order used for kswapd is passed to kcompactd
Future possible future uses for kcompactd include the ability to wake up
kcompactd on demand in special situations, such as when hugepages are
not available (currently not done due to __GFP_NO_KSWAPD) or when a
fragmentation event (i.e. __rmqueue_fallback()) occurs. It's also
possible to perform periodic compaction with kcompactd.
[arnd@arndb.de: fix build errors with kcompactd]
[paul.gortmaker@windriver.com: don't use modular references for non modular code]
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: David Rientjes <rientjes@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-03-17 21:18:08 +00:00
|
|
|
KCOMPACTD_WAKE,
|
2017-02-22 23:44:50 +00:00
|
|
|
KCOMPACTD_MIGRATE_SCANNED, KCOMPACTD_FREE_SCANNED,
|
2011-05-26 23:25:24 +00:00
|
|
|
#endif
|
|
|
|
|
#ifdef CONFIG_HUGETLB_PAGE
|
|
|
|
|
HTLB_BUDDY_PGALLOC, HTLB_BUDDY_PGALLOC_FAIL,
|
2021-05-05 01:37:19 +00:00
|
|
|
#endif
|
|
|
|
|
#ifdef CONFIG_CMA
|
|
|
|
|
CMA_ALLOC_SUCCESS,
|
|
|
|
|
CMA_ALLOC_FAIL,
|
2011-05-26 23:25:24 +00:00
|
|
|
#endif
|
|
|
|
|
UNEVICTABLE_PGCULLED, /* culled to noreclaim list */
|
|
|
|
|
UNEVICTABLE_PGSCANNED, /* scanned for reclaimability */
|
|
|
|
|
UNEVICTABLE_PGRESCUED, /* rescued from noreclaim list */
|
|
|
|
|
UNEVICTABLE_PGMLOCKED,
|
|
|
|
|
UNEVICTABLE_PGMUNLOCKED,
|
|
|
|
|
UNEVICTABLE_PGCLEARED, /* on COW, page truncate */
|
|
|
|
|
UNEVICTABLE_PGSTRANDED, /* unable to isolate on unlock */
|
|
|
|
|
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
|
|
|
|
|
THP_FAULT_ALLOC,
|
|
|
|
|
THP_FAULT_FALLBACK,
|
2020-04-07 03:04:28 +00:00
|
|
|
THP_FAULT_FALLBACK_CHARGE,
|
2011-05-26 23:25:24 +00:00
|
|
|
THP_COLLAPSE_ALLOC,
|
|
|
|
|
THP_COLLAPSE_ALLOC_FAILED,
|
2016-07-26 22:25:31 +00:00
|
|
|
THP_FILE_ALLOC,
|
2020-04-07 03:04:25 +00:00
|
|
|
THP_FILE_FALLBACK,
|
2020-04-07 03:04:28 +00:00
|
|
|
THP_FILE_FALLBACK_CHARGE,
|
2016-07-26 22:25:31 +00:00
|
|
|
THP_FILE_MAPPED,
|
2016-01-16 00:52:46 +00:00
|
|
|
THP_SPLIT_PAGE,
|
|
|
|
|
THP_SPLIT_PAGE_FAILED,
|
2016-03-17 21:18:45 +00:00
|
|
|
THP_DEFERRED_SPLIT_PAGE,
|
2024-08-30 10:03:39 +00:00
|
|
|
THP_UNDERUSED_SPLIT_PAGE,
|
2016-01-16 00:52:46 +00:00
|
|
|
THP_SPLIT_PMD,
|
2022-01-14 22:07:55 +00:00
|
|
|
THP_SCAN_EXCEED_NONE_PTE,
|
|
|
|
|
THP_SCAN_EXCEED_SWAP_PTE,
|
|
|
|
|
THP_SCAN_EXCEED_SHARED_PTE,
|
2017-03-10 00:17:00 +00:00
|
|
|
#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
|
|
|
|
|
THP_SPLIT_PUD,
|
|
|
|
|
#endif
|
2012-12-12 21:51:09 +00:00
|
|
|
THP_ZERO_PAGE_ALLOC,
|
|
|
|
|
THP_ZERO_PAGE_ALLOC_FAILED,
|
2017-09-06 23:22:30 +00:00
|
|
|
THP_SWPOUT,
|
mm, THP, swap: add THP swapping out fallback counting
When swapping out THP (Transparent Huge Page), instead of swapping out
the THP as a whole, sometimes we have to fallback to split the THP into
normal pages before swapping, because no free swap clusters are
available, or cgroup limit is exceeded, etc. To count the number of the
fallback, a new VM event THP_SWPOUT_FALLBACK is added, and counted when
we fallback to split the THP.
Link: http://lkml.kernel.org/r/20170724051840.2309-13-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Ross Zwisler <ross.zwisler@intel.com> [for brd.c, zram_drv.c, pmem.c]
Cc: Vishal L Verma <vishal.l.verma@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-06 23:22:52 +00:00
|
|
|
THP_SWPOUT_FALLBACK,
|
2011-05-26 23:25:24 +00:00
|
|
|
#endif
|
2014-10-09 22:29:32 +00:00
|
|
|
#ifdef CONFIG_MEMORY_BALLOON
|
|
|
|
|
BALLOON_INFLATE,
|
|
|
|
|
BALLOON_DEFLATE,
|
|
|
|
|
#ifdef CONFIG_BALLOON_COMPACTION
|
|
|
|
|
BALLOON_MIGRATE,
|
|
|
|
|
#endif
|
|
|
|
|
#endif
|
2014-01-21 22:33:16 +00:00
|
|
|
#ifdef CONFIG_DEBUG_TLBFLUSH
|
2013-09-11 21:20:23 +00:00
|
|
|
NR_TLB_REMOTE_FLUSH, /* cpu tried to flush others' tlbs */
|
|
|
|
|
NR_TLB_REMOTE_FLUSH_RECEIVED,/* cpu received ipi for flush */
|
|
|
|
|
NR_TLB_LOCAL_FLUSH_ALL,
|
|
|
|
|
NR_TLB_LOCAL_FLUSH_ONE,
|
2014-01-21 22:33:16 +00:00
|
|
|
#endif /* CONFIG_DEBUG_TLBFLUSH */
|
mm, swap: add swap readahead hit statistics
Patch series "mm, swap: VMA based swap readahead", v4.
The swap readahead is an important mechanism to reduce the swap in
latency. Although pure sequential memory access pattern isn't very
popular for anonymous memory, the space locality is still considered
valid.
In the original swap readahead implementation, the consecutive blocks in
swap device are readahead based on the global space locality estimation.
But the consecutive blocks in swap device just reflect the order of page
reclaiming, don't necessarily reflect the access pattern in virtual
memory space. And the different tasks in the system may have different
access patterns, which makes the global space locality estimation
incorrect.
In this patchset, when page fault occurs, the virtual pages near the
fault address will be readahead instead of the swap slots near the fault
swap slot in swap device. This avoid to readahead the unrelated swap
slots. At the same time, the swap readahead is changed to work on
per-VMA from globally. So that the different access patterns of the
different VMAs could be distinguished, and the different readahead
policy could be applied accordingly. The original core readahead
detection and scaling algorithm is reused, because it is an effect
algorithm to detect the space locality.
In addition to the swap readahead changes, some new sysfs interface is
added to show the efficiency of the readahead algorithm and some other
swap statistics.
This new implementation will incur more small random read, on SSD, the
improved correctness of estimation and readahead target should beat the
potential increased overhead, this is also illustrated in the test
results below. But on HDD, the overhead may beat the benefit, so the
original implementation will be used by default.
The test and result is as follow,
Common test condition
=====================
Test Machine: Xeon E5 v3 (2 sockets, 72 threads, 32G RAM)
Swap device: NVMe disk
Micro-benchmark with combined access pattern
============================================
vm-scalability, sequential swap test case, 4 processes to eat 50G
virtual memory space, repeat the sequential memory writing until 300
seconds. The first round writing will trigger swap out, the following
rounds will trigger sequential swap in and out.
At the same time, run vm-scalability random swap test case in
background, 8 processes to eat 30G virtual memory space, repeat the
random memory write until 300 seconds. This will trigger random swap-in
in the background.
This is a combined workload with sequential and random memory accessing
at the same time. The result (for sequential workload) is as follow,
Base Optimized
---- ---------
throughput 345413 KB/s 414029 KB/s (+19.9%)
latency.average 97.14 us 61.06 us (-37.1%)
latency.50th 2 us 1 us
latency.60th 2 us 1 us
latency.70th 98 us 2 us
latency.80th 160 us 2 us
latency.90th 260 us 217 us
latency.95th 346 us 369 us
latency.99th 1.34 ms 1.09 ms
ra_hit% 52.69% 99.98%
The original swap readahead algorithm is confused by the background
random access workload, so readahead hit rate is lower. The VMA-base
readahead algorithm works much better.
Linpack
=======
The test memory size is bigger than RAM to trigger swapping.
Base Optimized
---- ---------
elapsed_time 393.49 s 329.88 s (-16.2%)
ra_hit% 86.21% 98.82%
The score of base and optimized kernel hasn't visible changes. But the
elapsed time reduced and readahead hit rate improved, so the optimized
kernel runs better for startup and tear down stages. And the absolute
value of readahead hit rate is high, shows that the space locality is
still valid in some practical workloads.
This patch (of 5):
The statistics for total readahead pages and total readahead hits are
recorded and exported via the following sysfs interface.
/sys/kernel/mm/swap/ra_hits
/sys/kernel/mm/swap/ra_total
With them, the efficiency of the swap readahead could be measured, so
that the swap readahead algorithm and parameters could be tuned
accordingly.
[akpm@linux-foundation.org: don't display swap stats if CONFIG_SWAP=n]
Link: http://lkml.kernel.org/r/20170807054038.1843-2-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Tim Chen <tim.c.chen@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-06 23:24:29 +00:00
|
|
|
#ifdef CONFIG_SWAP
|
|
|
|
|
SWAP_RA,
|
|
|
|
|
SWAP_RA_HIT,
|
mm: count zeromap read and set for swapout and swapin
When the proportion of folios from the zeromap is small, missing their
accounting may not significantly impact profiling. However, it's easy to
construct a scenario where this becomes an issue—for example, allocating
1 GB of memory, writing zeros from userspace, followed by MADV_PAGEOUT,
and then swapping it back in. In this case, the swap-out and swap-in
counts seem to vanish into a black hole, potentially causing semantic
ambiguity.
On the other hand, Usama reported that zero-filled pages can exceed 10% in
workloads utilizing zswap, while Hailong noted that some app in Android
have more than 6% zero-filled pages. Before commit 0ca0c24e3211 ("mm:
store zero pages to be swapped out in a bitmap"), both zswap and zRAM
implemented similar optimizations, leading to these optimized-out pages
being counted in either zswap or zRAM counters (with pswpin/pswpout also
increasing for zRAM). With zeromap functioning prior to both zswap and
zRAM, userspace will no longer detect these swap-out and swap-in actions.
We have three ways to address this:
1. Introduce a dedicated counter specifically for the zeromap.
2. Use pswpin/pswpout accounting, treating the zero map as a standard
backend. This approach aligns with zRAM's current handling of
same-page fills at the device level. However, it would mean losing the
optimized-out page counters previously available in zRAM and would not
align with systems using zswap. Additionally, as noted by Nhat Pham,
pswpin/pswpout counters apply only to I/O done directly to the backend
device.
3. Count zeromap pages under zswap, aligning with system behavior when
zswap is enabled. However, this would not be consistent with zRAM, nor
would it align with systems lacking both zswap and zRAM.
Given the complications with options 2 and 3, this patch selects
option 1.
We can find these counters from /proc/vmstat (counters for the whole
system) and memcg's memory.stat (counters for the interested memcg).
For example:
$ grep -E 'swpin_zero|swpout_zero' /proc/vmstat
swpin_zero 1648
swpout_zero 33536
$ grep -E 'swpin_zero|swpout_zero' /sys/fs/cgroup/system.slice/memory.stat
swpin_zero 3905
swpout_zero 3985
This patch does not address any specific zeromap bug, but the missing
swpout and swpin counts for zero-filled pages can be highly confusing and
may mislead user-space agents that rely on changes in these counters as
indicators. Therefore, we add a Fixes tag to encourage the inclusion of
this counter in any kernel versions with zeromap.
Many thanks to Kanchana for the contribution of changing
count_objcg_event() to count_objcg_events() to support large folios[1],
which has now been incorporated into this patch.
[1] https://lkml.kernel.org/r/20241001053222.6944-5-kanchana.p.sridhar@intel.com
Link: https://lkml.kernel.org/r/20241107011246.59137-1-21cnbao@gmail.com
Fixes: 0ca0c24e3211 ("mm: store zero pages to be swapped out in a bitmap")
Co-developed-by: Kanchana P Sridhar <kanchana.p.sridhar@intel.com>
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Usama Arif <usamaarif642@gmail.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Cc: Hailong Liu <hailong.liu@oppo.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-11-07 01:12:46 +00:00
|
|
|
SWPIN_ZERO,
|
|
|
|
|
SWPOUT_ZERO,
|
2022-03-22 21:46:33 +00:00
|
|
|
#ifdef CONFIG_KSM
|
|
|
|
|
KSM_SWPIN_COPY,
|
|
|
|
|
#endif
|
2021-05-05 01:38:03 +00:00
|
|
|
#endif
|
2022-04-29 06:16:16 +00:00
|
|
|
#ifdef CONFIG_KSM
|
|
|
|
|
COW_KSM,
|
|
|
|
|
#endif
|
2022-05-19 21:08:53 +00:00
|
|
|
#ifdef CONFIG_ZSWAP
|
|
|
|
|
ZSWPIN,
|
|
|
|
|
ZSWPOUT,
|
2023-11-30 19:40:21 +00:00
|
|
|
ZSWPWB,
|
2022-05-19 21:08:53 +00:00
|
|
|
#endif
|
2021-05-05 01:38:03 +00:00
|
|
|
#ifdef CONFIG_X86
|
|
|
|
|
DIRECT_MAP_LEVEL2_SPLIT,
|
|
|
|
|
DIRECT_MAP_LEVEL3_SPLIT,
|
2025-01-26 07:47:27 +00:00
|
|
|
DIRECT_MAP_LEVEL2_COLLAPSE,
|
|
|
|
|
DIRECT_MAP_LEVEL3_COLLAPSE,
|
2023-02-27 17:36:27 +00:00
|
|
|
#endif
|
|
|
|
|
#ifdef CONFIG_PER_VMA_LOCK_STATS
|
|
|
|
|
VMA_LOCK_SUCCESS,
|
|
|
|
|
VMA_LOCK_ABORT,
|
|
|
|
|
VMA_LOCK_RETRY,
|
|
|
|
|
VMA_LOCK_MISS,
|
2014-06-04 23:06:46 +00:00
|
|
|
#endif
|
2024-07-24 20:33:21 +00:00
|
|
|
#ifdef CONFIG_DEBUG_STACK_USAGE
|
|
|
|
|
KSTACK_1K,
|
|
|
|
|
#if THREAD_SIZE > 1024
|
|
|
|
|
KSTACK_2K,
|
|
|
|
|
#endif
|
|
|
|
|
#if THREAD_SIZE > 2048
|
|
|
|
|
KSTACK_4K,
|
|
|
|
|
#endif
|
|
|
|
|
#if THREAD_SIZE > 4096
|
|
|
|
|
KSTACK_8K,
|
|
|
|
|
#endif
|
|
|
|
|
#if THREAD_SIZE > 8192
|
|
|
|
|
KSTACK_16K,
|
|
|
|
|
#endif
|
|
|
|
|
#if THREAD_SIZE > 16384
|
|
|
|
|
KSTACK_32K,
|
|
|
|
|
#endif
|
|
|
|
|
#if THREAD_SIZE > 32768
|
|
|
|
|
KSTACK_64K,
|
|
|
|
|
#endif
|
|
|
|
|
#if THREAD_SIZE > 65536
|
|
|
|
|
KSTACK_REST,
|
|
|
|
|
#endif
|
|
|
|
|
#endif /* CONFIG_DEBUG_STACK_USAGE */
|
2011-05-26 23:25:24 +00:00
|
|
|
NR_VM_EVENT_ITEMS
|
|
|
|
|
};
|
|
|
|
|
|
2016-07-26 22:25:31 +00:00
|
|
|
#ifndef CONFIG_TRANSPARENT_HUGEPAGE
|
|
|
|
|
#define THP_FILE_ALLOC ({ BUILD_BUG(); 0; })
|
2020-04-07 03:04:25 +00:00
|
|
|
#define THP_FILE_FALLBACK ({ BUILD_BUG(); 0; })
|
2020-04-07 03:04:28 +00:00
|
|
|
#define THP_FILE_FALLBACK_CHARGE ({ BUILD_BUG(); 0; })
|
2016-07-26 22:25:31 +00:00
|
|
|
#define THP_FILE_MAPPED ({ BUILD_BUG(); 0; })
|
|
|
|
|
#endif
|
|
|
|
|
|
2011-05-26 23:25:24 +00:00
|
|
|
#endif /* VM_EVENT_ITEM_H_INCLUDED */
|
